The above referenced copending application discloses a slump filling apparatus for a packerhead/vibration system concrete pipe machine, the slump filler having an overfill and compaction ring assembly mounted on the top of the pipe mold or jacket which enables complete formation of the concrete pipe in single stage fashion without necessity of adding extra concrete to the top of the jacket to make up for volume lost in compaction of the material caused by vibration. The slump filler is useful with any one of a wide variety of available concrete pipe machines, and basically includes an overfill and compression ring assembly surmounting the pipe jacket which has a downwardly driven compression ring to compress overfill concrete into the top of the pipe jacket during the final stages of manufacture of a green pipe to complete the top of spigot end of the pipe, both the vibration and the compression ring causing the overfill to compact into the pipe jacket.
In the type of concrete pipe machines being discussed, a vertically disposed pipe jacket is used as a form for the pipe to be made, having a lower bell forming end and an upper spigot forming end. Interiorally of the upper periphery of the pipe jacket is a cap which completes the formation of the pipe spigot end. Such caps are of two varieties: "open" and "closed". An "open" bore cap covers only about one-half of the outer periphery of the spigot end of the pipe, the remaining half being formed by the compression ring of the slump filler, which acts directly on overfill concrete concentrically interiorally of the open bore cap, the open bore cap remaining stationary during operation of the slump filler, as shown in FIGS. 6 and 7 of the slump filler application.
Conversely, a "closed" bore cap covers and forms substantially the entire outer periphery of the spigot end of the pipe. Thus, when the slump filler is used with closed bore caps, the entire cap must be moved from an elevated, overfill accomodation position, to a lower, spigot end forming disposition, the compression ring of the slump filler acting directly on the closed bore cap to compress overfill concrete into the pipe jacket, since there is no room for the compression ring to act directly on the overfill concrete.
Thus, when utilizing a closed bore cap, a support assembly is required to retain the closed bore cap in an elevated position as the pipe is formed and the support for the closed bore cap must be releasable during actuation of the slump filler so that the closed bore cap may move downwardly into the top end of the pipe jacket to complete the pipe spigot end. To accomplish the foregoing operation one initial attempt utilized a hydraulically actuated cap support assembly which was found to be not entirely satisfactory. The presently disclosed and claimed cap rest assembly evolved from the earlier attempt.